Safety harness device



Aug. 13,.'1963 Filed Nov. 23, 1959 RfJ. WRIGHTON SAFETY HARNESS DEVICE w he 63 3 Sheets-Sheet 1 Fig. 3

IN VENTOR Robert J Wrighron Aug. 13, 1963 R. J. wRlGHToN i 3,100,609

SAFETY HARNESS DEVICE Filed Nov. 23, 1959 3 Sheets-Sheet 2 INVENTOR y E Anz- Attorney Aug.1 13, 1963 R. J. wRlGHToN 3,100-,609

SAFETYl HARNESS DEVICE:

Filed Nov. 23, 1959 3 Sheets-Sheet 3 INV ENTOR Robert J. Wrighon f ma gard Attorney United States Patent O 3,100,609 SAFETY HARNESS DEVICE Robert J. Wrightnn, Newport Beach, Calif., assigner to Pacific Scientific Company, San Francisco, Calif., a corporation of California t Filed Nov. 23, 1959, Ser. No. $54,369 Claims. (Cl. 26E- 1014) This invention relates, in general, to safety harness devices for use in protecting persons in moving vehicles, and, more particularly, to a novel improved inertiaoperated safety device utilized to lock automatically persons, such `as airplane pilots, in their seats during crashes and the like.

The present safety harness device is responsive to the rate of acceleration of the pilot, passenger or user, with respect to his seat and operates directly in response to the `tensions exerted on a cable or webbing resulting from forces applied to the webbing through the pilots shoulder harness by movements of his body, the device operating automatically upon sudden violent movement of the body to secure the pilot or user safely in his seat. This present invention discloses a novel type of such inertiaoperated device which incorporates novel improved features over prior art safety devices.

rThe principal object of the present invention is to provide an exceedingly light-weight, rugged and dependable safety harness device operating on the principle of rate of acceleration of the harness cable or webbing to retain the user in his sea-t Iin the event of sudden or dangerous movement of the vehicle, the device incorporating various safety features enhancing its dependability in use.

One feature of the present invention is the provision of an inertia-operated safety device lwherein the cable or webbing is locked up automatically should is exceed a certain lacceleration due to the pull exerted thereon by the pilot or user thereof, the safety `device being provided with a novel means for preventing the reel from relooking during that instant of time that the reel is being unlocked, thereby preventing the reel from locking fwhen a tension is exerted thereon by the'pilot.

Another feature of the present invention is the provision of an inertia-operated safety device provided with a novel automatic unlock mechanism for automatically unlocking the device when the acceleration force causing the lock-up has been removed from the webbing or cable.

These and other features and advantages of this invention -will become `apparent after perusal of the followin-g description of this invention `disclosed in `the drawings wherein:

FlG. 1 isa front elevation view of one embodiment of the present invention utilized in a reel type of safety device having a webbing tension member;

FIG. 2 is an end view partly cu-t away of the apparatus taken along section line 2 2 of FIG. 1 in the direction of the arrows;

FIG. 3 is a longitudinal section View of the apparatus taken `along section line 3 3 of FIG. 2 in the direction of the arrows;

FIG. 4 is a longitudinal view partly in section of the apparatus taken along `section line 4 4 in FIG. 2;

FIG. 5 is a cross-section view of the apparatus taken along sec-tion line 5 5 of FIG. 3;

FIG. 5a is a cross-section view of a portion of the device showing the method of coupling the webbing to the shaft or reel;

FlG. 6 is a crosssection view of the novel device taken' along section line 6 6 in FIG. 4 showing the device in its locked position;

7. ls a cross-section View of the device, also in the locked position, taken along section line 7 7 in FIG. 3;

3,109,699 Patented Aug. 13, 1963 F EG. 8 is a cross-section of the device taken Ialong section line 8 3 inI FIG. 3;

FIG. 9 is an end view of the device in its unlocked position, taken lalong the section line 9 9 in FIG. 4, with the end cover removed;

FIG. 10 is a cross-section view of La portion of the device taken along section line 11i-lll` in FlG. 9;

FG. 11 is a cross-section view of `a portion of the device taken along section line 11 11 in FIG. 10;

FIG. l2 is .a cross-section view of this novel device wherein an automatic unlocking mechanism is disclosed for use at times in lieu of the manual unlock mechanism, and

FIG. 12a is a cross-section view of a portion of the device of FIG. 12 taken along section line 12a-12a.

Similar characters of reference are used in the above figures to designate corresponding parts.

Although the present embodiment is a reel and webbing type of inertia-operated safety device, it should be understood that this invention applies equally well to cable and reel types as well as other types of safety devices. A `complete detailed `description of the construction of this -device will first be given, followed by a full explanation of its operation.` A safety reel of this general typeQ has been disclosed and claimed in U.S. patent application Serial No. 644,270 led on March 6, 1957, by Clifford E. Cushman and Robert l. Wrighton, entitled Safety Harness Device, now Patent 3,018,065 issued January 23, 1962, the present reel incorporating new and improved features which are specifically disclosed and claimed in ythis application.

Referring now to the drawings, this safety apparatus comprises a metallic casing 11 as of `aluminum alloy having `a removable end cover 12 secured thereon. Integral lugs 13 are provided on the casing 11 for mounting the safety device on a seat or the like. This device may be mounted in a horizontal position as shown in FIG. 5, in which event the tension member or webbing 14 may extend through opening `15 in Ithe casing as shown in dotdash lines; or it may be mounted on Ia vertical surface, that is, rotated clockwise with respect to FIG. 5, in Vwhich event the webbing 14 may extend out through the opening 16 in the casing 11.

Located within the casing 11 is a wall 17 having a central opening `therein which serves as a bearing for one end of the webbing reel shaft 13, the opposite end of reel or shaft 18` being rotatably mounted in an 1annular cupshaped wall member i9. The central section of shaft 18 is enlarged and has an' elongated slot 21 therethrough, the slot being wider on one side of the shaft `than on the other (see FIGS. 5 and 5a).

The webbing 14, the outer end of which is adapted to be coupled to the shoulder harness of the pilot, is removably mounted at its inner end to the shaft 18 within the elongated slot 21 in such manner that the 'webbing 14 may be easily Aand rapidly removed from the shaft 18 for replacement without dismantling this device. TheV inner end of webbing 14 is firmly embedded in an elongated plastic end termination 22 having a substantially rectangular `cross-section. A pair of elongated webretaining inserts 23 and 24 as of metal are provided, between which the end termination 22 is sandwiched, the inserts 23, 24 `and termination 22 being `snugly wedged within the slot 21 in shaft 18 from its -wide side. 'Ihe webbing 14 extends out through the narrow side of .the slot 21 and around the shaft 18. To 4remove the webbing 14 from the device, the webbing is fully unwound from the `shaft 13 and then the termination 22 is pushed out from the slot 2.1 in the shaft 18, the inserts 23 and 24 permitting easy decouplingwand the webbing withdrawn through ,either of the openings 15 and 16. A

t 3 new webbing may then be threaded into the slot 21 and pulled through until its termination 22 is embedded in the slot 21.

A spiral power spring 25 encircles the right-hand end (FIG. 3) of the shaft 18, the inner lend of the spring 25 being secured to the shaft '18 and the outer end to the cup-shaped wall member 19. The spring 25 is so tensioned 'as lto rotate the shaft 13 :to wind the webbing 14 thereo-n. A protective end cover 26 is provided and is held in place Iby retaining rings 27. The end cover 26 is provided with a central opening 26' through which a hexagonal wrench may be inserted into the hexagonal opening 2S in the shaft 18 so that the shaft 18 rnay be held in any position against the tension of spring 25. Thus, the shaft 18 may he held in the position in which the webbing 14 is fully unwound from the shaft 18, so that the webbing -14 may be removed land replaced with new webbing. An annular webbing shield 29 is provided on the shaft 18. Integral with lthe shaft x18 is a ratchet 30 located adjacent the wall 17.

An annular iiywhel 3&1 is rotatably mounted on the shaft 1S and is held in place by means of a retaining ring 32. =Fixedly secured on the shaft 18 so as to rotate therewith is a torque -plate 33 having a torque pin 34 embedded therein. The torque pin 34 extends through an opening 35 in the flywheel and is snugly fitted a slot 36 in a substantially triangular-shaped thrust plate 37 which is rotatably mounted on the shaft 18. A compensator -screw 38 is screwed into a threaded bore in the left-hand end portion (FIG. 3) ofthe shaft 18. A helical thrust plate spring 39 encircles the screw 3S and is` compressed between the head 381 of screw 38 and the thrust plate 37. Three steel balls 41 are sandwiched between the thrust plate 37 :and the left-hand surface of the ilywheel 31, Ithe balls nesting in indentations in the thrust plate and flywheel surfaces. Thus, the thrust plate 37 is at all times pressed against the steel balls 31 which i-n turn are pressed against the liywheel 31.

An annular retraction `anti-lock member 42 (FIGS. 3 and 7) having radially extending lingers is rotatably mounted on the shaft 18 between the torque plate 33 and wall 17. One of said lingers 43 has a slot in the end thereof. An anti-lock lever 44 is pivotally mounted on the torque pin 34, `the lever 44 having a small drive pin 45 embedded therein. The outer end of the drive pin `45 extends into .the slot in finger 43. The `outer end 46 of `lever 44 has la notch therein adapted to accommodate vone edge `47 of an opening eut into the periphery of the iiywheel 311. The yoperation of this anti-lock mechanism will be fully explained hereinafter.

. A sear ,pivot pin `48 is mounted in the casing 11 off `to one side of the main `axis through the shaft 18 (see particularly IFIGS. 3, 4, 9 :and `10). A U-shaped sear 49 is pivotally mounted on pin 48 and held in place by retaining rings 51. A second U-shaped sear 60' is also pivotally mounted on pin I48 `st-raddlinig the sear 49, this second sear being provided with 4an extension arm `and cam 66. V'Ihe shaft 13 extends through an opening in the base surface 52 of the sear 49 and also sear 60. A helical sear spring 53 encircles the compensator screw 38 and is compressed between the head 38' of the screw 3S and the base surface S2 of the sear 49, the undersurface of 4said sear base 52 (as viewed in FIG. 10i) having la dimple 54 which presses firmly against the second sear `611 which in turn presses against .the plate 37. Two integr-al lingers '55 and 56 extend from the base 52 of sear 49.

One leg 57 of the sear l49 is provided with a pro- `jection 58 adapted to tbe engaged lby a pin 59 `set olf-center on an 4auxiliary control rod 61 rotatably mounted in the casing 11. Control rod 61 is secured -to an auxiliary controllever 62 outside -o-f the Vcasing 1'1.

A main lcontrol shaft 63 is rotatably mounted in the casing :11 and is secured to an external control lever 64 which, as will lbe explained subsequently, serves as the main control for manually locking and releasing this safety device. An -inner control lever 65 is hxedly secured to the shaft 63, the louter end of the lever 65 having .a control shaft torque pin 66 embedded therein. A dog retraction lever 67 is loosely mounted on the main control shaft 63 adjacent the inner control lever 65, the control shaft torque pin 66 extending through a slightly enlarged -opening in the dog retraction lever 67. A control shaft spring 68 is compressed between a pin 69 mounted in cont-rol lshaft 63 and the dog retraction lever 67. Thus, dog retraction lever 67 may not rotate relative to shaft 63, .except very slightly since the opening in lever 67 accommodating torque pin 66 is sli-ght-ly enlarged, but lever 67 may move longitudinally relative to shaft 63 against the tension of spring |68 for reasons set forth hereinafter. The outer end of torque pin 66 is adapted to engage linger 56 of sear 49.

A lock dog shaft 71 is tixedly secuned within the casing 11 off Ito one -side of the main shaft 18 (see FIGS. 4, 6, 7, 9 and 110). A lock dog 72 is rotatably mounted on the lock dog yshaft 71 in a position to engage the teeth on ratchetwheel 30 in locking fashion. A spring 73 is provided encircling said shaft 71 and engaging an elongated finger 74 integral with and extending from the lock dog 7 Z, the spring being tensioned so as to tend to urge the lock dog 72 into locking engagement with the ratchet wheel 39. The outer end of the elongated finger 74 is crooked slightly land engages the outer end of finger 55 on sear 49. A second lfinger '75 integral with the lock tapered dog 72 extends out from the dog, its tapered end surface engaging the outer end of dog retraction lever `67.

An tanti-rebound lever 76 is movably mounted on lock- `dog shaft 71, a spring 77 urging the lever in a downward 'direction as viewed :in FIG. 10. A projection 78 on lever 76 4forms a stop against the internal surface 79 of casing 11 to permit the free end 81 of lever 76 to -rdrop only a iixed distance. Slight extensions -8'2 and 83 of lever 76 engage inner surfaces of casing r11 to prevent any rotational rnovement of lever 76 on shaft 71. A slight projection 84 on the lever 76 is adapted to ride on the outer end of finger 74 of lock tdog 72 when lock dog 72 is not engaging the ratchet wheel 30 and to drop down behind the linger 74 'when the lock dog rotates into engagement with the ratchet wheel, as will be subsequently explained. The pin 69 in control shaft 63 is arranged to engage the tilted end 85 of the anti-rebound lever 76.

A detailed description of the operation of this novel device embodying the presentrinvention will now be given with reference'to its use by a pilot in an aircraft. The apparat-us is shown in its normal operating position in FIGS. l through 5 and 8 through l0, that is to say, when it has not been manually or automatically locked. As the pilot moves about in his seat in a normal manner to control his craft, his shoulder harness likewise moves and pulls on the webbing y14. The webbing unwinds from the webbing shaft 18, the shaft rotating counter-clockwise (FIG. 5) land with it the integral ratchet wheel 30u As the shaft rotates, it carries the torque plate 33 with it, and, through torque pin 34, also rotates the thrustplate 37. Since the thrust plate 37 is pressed against the steel balls 41 and thus engages the flywheel y31, the flywheel is rotated zalong with the shaft 18. In winding up, when the force is relaxed on the webbing 14, the power spring rotates the shaft 18 clockwise (FIG. 5) along with the'iiywheel 31.

Should the pilot desire to secure himself safely in his seat when, for example, a crash is imminent, he leans back in his seat and the slack in the harness is taken up by the safety device. The pilot then operates the main control lever 64 by a suitable control cable (not shown);

thereby rotating the inner control lever 65 clockwise, as viewed in FIGS. 9 and ll. The control shaft torque pin 66 engages the outer end of finger 56 on sezar 49 and slides thereunder, the pin 66 raising the finger 56 and frs with it the linger 5S until the end of spring-loaded linger 74 on lock dog 72 can slip under linger 55, thus permitting lock dog 72 [to rotate counter-clockwise as viewed in FIG. 9 into locking engagement with the teeth of ratchet wheel 30 (see FIG. 6). The lock dog retraction lever 67 rotates with the pin 66 and rides up and over the inclined end surface of the lock dog finger 75. vIf the pilot manually locks the device while leaning forward, the power spring 25 will still rotate the shaft 13 when the pilot -sits back thereby to reel in the slack, the lock dog 72 falling in behind each successive ratchet tooth.

This device will thereafterl remain clocked until the inner control lever 65 is manually rotated counter-clockwise as viewed in FIGS. 9 .and ll to release the device. When rotated in the release direction, the outer end of lock dog retraction lever 6-7 engages the back side of the inclined lock dog linger 75 and drives the linger 75, and thus the lock dog, back to the release position, where the sear finger 55 falls down behind the projecting linger 74 to hold the lock dog in the released position shown in FIGS. 9 and ll.

The novel `appanatus of this invention will automatical- 1y operate to lock up the webbing 14 during crashes and the like if the pilot does not manually lock it. This safety device is so arranged that when any loading on the webbing 14 causing an acceleration of a particular number of Gs or over occurs, depending on the setting of the device, this webbing 14 will be locked up. Assume that the aircraft in landing strikes an object and decelerates rapidly, pitching the pilot forward in his seat, or that the craft yawsA or descends suddenly, so that the pilots body exerts a loading of this panticular number of Gs acceleration on the cable 7. When the sharp jerk occurs on the webbing 14, it tends .to rotate the shaft 18, torque plate 33, and, through pin 34, thrust plate 37, fat a rapid rate of acceleration. The thrust plate 37, through steel balls 41, tends to rotate the flywheel 31 along with the shaft 18, but this ywheel is made of a relatively heavy metal mass, and it tends to remain stationary when the force is first applied. This tendency of the ywheel to remain stationary overcomes the springloading force of the thrust plate and there is, therefore, a relative rotational movement between the thrust plate 37 and the ily-wheel 31, and this causes the thrust plate to ride up on the steel balls and move to the let as viewed in FIG. 3, or move upwardly as viewed in FIG. 10. The thrust plate 37, through sear 60, bears against the dimple 54 in sear 49, thus rotating sear 49 about its pivot pin 418 against the Itension of sear spring 53. The sear linger 55 is thus disengaged from the lock dog linger 74 and the lock dog 72 rotates under pressure of spring 73 to engage the ratchet teeth and thus locks the ratchet wheel 30 to prevent paying out of webbing 14, and hence retains the user in his seat. In this automatically-locked position, the apparatus will still reel in the webbing should the user move back in his seat in the same manner as explained above when manually locked.

The sear spring 53 is utilized to control the exact number of Gs of acceleration on the webbing which are necessary to lock this safety device automatically. The tension of sear spring 53 may be varied by screwing the compensation screw 38 into or out of the shaft 18 to increase or decrease the tension, and thus raise or lower the G value of operation. The screw 36 may be rotated in 90 segments and held in position by means of the holding pin 40x The components of this safety device may be selected as to size, weight, etc.,-so that the device may cover wide ranges of accelerations. In one embodiment of this device constructed, the locking acceleration was set at 2 Gs.

To release from the 'automatic lock position, the pilot rotates the lever device 64 to the manual lock position such that the lock dog retraction lever 67 rides up and over the inclined end of lock dog linger 75. Reverse rotation of lever 64 then causes the retnaction lever 67 to engage the finger 75 and rotate the lock dog 72 to its release position, where sear linger 55l falls behind the projecting finger 74 to hold the lock dog in the released position.

This safety device is provided with an anti-rebound means for preventing the lock dog 72, once it has been freed to contact the ratchet wheel `3l1 and lock this device, from falsely releasing, that is returning to the normal unlocked position before manual release by the pilot. This false release could possibly occur, for example, if the device were locked initially with a portion of the webbing ldunwound from the shaft 18. When the shaft rotates under the power of spring 2S to ytake up the slack, the lock dog 72 rides over the teeth of the ratchet wheel 30 and has a tendency to bounce. If the lock dog were to bounce high enough and linger 74 were to move out from under sear ringer 55, the device would be released. Anti-rebound lever 76 prevents such false operation. The central section of this lever 76 rests on the end of lock dog linger 74 under the pressure of spring 73 when the lock dog 72 is in its normal unlocked position. When the lock dog rotates into contact with the ratchet wheel 30, however, the projection S5 on springloaded lever 76 drops behind the finger '74 and prevents the finger 74 from subsequently moving ont from under the -sear finger S5. When control shaft 63 is rotated to release this safety device as described above, pin 69 in shaft 63 engages and lifts the end 81 of lever 76 and thus allows the end of lock dog finger 74 to move out from under sear linger 55.

This safety device is also provided with a novel means for preventing the reel from relooking during the period that the reel is lbeing unlocked, such relooking, for example, ordinanily occurring if the reel is unlocked at a time when a substantial load, for example 25 lbs., is being exerted on thel harness strap or cable; such a load could occur, of course, if the pilots body is placing a strain on the strap at the same time he is openating the unlocking mechanism. This stress in the cable or webbing ywould be sutlioient at times, when transmitted to the acceleration sensing flywheel, to cause the flywheel to actuate and relock the reel. This `novel lock-up preventing means includes the second U-shaped sear device 66. As the control shaft 63 is rotated to release this safety device Ifrom lock-up, as `described above, the pin 69, in addition to lifting the end 81 of lever 76, rides over the earn all of the second sear 6@ and prevents movement of the sear 60 in the vertical `direction las viewed in FIG. l0'. The base of this second sear rests firmly against the thrust plate 37 `and thus restrains upward movement of the thrust plate 37 (as viewed in FIG. l0) due to any tendency for relative rotation between the ilywheel 31 and the spool 18. It can therefore be seen that no lockup of this device can occur during the time that the pin 69 extends over the cam 60. When the control shaft 63, and thus pin 69, are returned to their normal position, the second sear 60' is free to move, and thus the automatic lock feature is returned to normal operation.

It is understood that this safety device works on the principle that the inertia flywheel 31 tends to remain stationary when an angular acceleration of the webbing reel 18 and thrust plate is produced, the rotational movement of the harness reel relative to the inertia member resulting in the automatic locking of the webbing. If the webbing 14 is reeled in at excessive speeds, the inertia flywheel will tend to keep rotating when the webbing reel 18` is brought to a sudden stop Iby a retarding force acting on the webbing 14. Any resultant rel-attive rotation between the flywheel and thrust plate 37 may result in a tipping of the sear 11i-9 and automatic locking when it is not desired. An antilocking apparatus is utilized in this safety device and is clearly seen in FIG. 7. This antilocking structure, effective only during rotation of the webbing shaft 1S in the wind-up direction, comprises antilock member 42 rotatably mounted on the shaft 13 and having a plurality of radially extending fingers which bear -fnictionally against the stationary wall 1'7. As viewed in FIG. 7, as the webbing shaft 18 rotates clockwise in the unwind direction, the torque plate 33` and torque pin 34 rotate with the shaft 13. Thus, the anti-lock lever @A pivotally mounted on pin 34 tends to drive the anti-lock member rotationvally with the shaft 18 through drive pin 4S and slotted finger d3. However, due to the frictional bearing of the fingers of member 4Z on the wall 17, the member 42 resists rotation and thus causes anti-lock lever 44 to pivot counter-clockwise so that its end 46 moves out of contact with the edge 47 of the opening in the flywheel 31, thus freeing flywheel 31 so that it may rotate relative to the shaft 18 for automatic locking purposes during webbing unwinding. After lever 4d is disengaged from `the flywheel 31, the anti-lock member 4.2i rotates with the shaft 18. As the shaft 18 commences to rotate counter-clockwise in the windup direction, member 42 due to its drag on wall 17, resists rotation and anti-lock lever 44 is driven by pin 45 in a. clockwise pivotal direction until end 46 engages iiywheel 31 at edge 47. The flywheel is thus coupled to the webbing shaft `18 during webbing wind-up and may not, therefore, rotate relative to the shaft 18 during wind-up. Thus, this safety device may not automatically lockup during wind-up regardless of the angular acceleration of the webbing shaft 1S.

An auxiliary control lever `62, is provided which will operate to lock this device independently of the automatic inertia-operated locking means and the manual control means y63 and 64. lf, for example, the device is utilized in an aircraft provided with ejection seats where the safety device is usually mounted on the seat, the pilot, while preparing for ejection, turns the lever 62 clockwise as viewed in FIG. l0. The pin S9 engages the projection 58 and thus raises Athe sear 49, allowing lock-dog iinger 74 to pass under sear finger 55, while lock-dog 72 rotates to engage and lock the ratchet wheel 30. Manual control 63, 64 thereafter has no control over the device until auxiliary control lever L62 isreturned to its normal position as shown in FIG. 10.

This inertia-operated safety device operates on rectilinear acceleration of the webbing 14, which, of course, is converted to angular acceleration of the shaft 1S and webbing wound thereon, the locking mechanism responding to a particular angular acceleration to automatically lock. For a given rectilinear acceleration of the webbing 14, the angular acceleration of the shaft 1S and webbing i 14 wound thereon varies as the effective radius of the shaft and webbing varies. Thus, `a certain rectilinear acceleration of the webbing, with the webbing almost unwound from the shaft 1S, produces an angular acceleration of the shaft 1S which is much greater than if the webbing had been fully wound on the shaft 1S. This, of course, would result in the device operating over an undesired range of rectilinear acceleration values rather than at one specific `value of G, for example, 2 Gs. There in included in the safe-ty device a compensating mechanism for automatically compensating for variations in effective shaft and webbing radius by changing the angular acceleration at which the device will lock to ensure operation of this device at one particular rectilinear acceleration. Thecompensator screw 38 screwed into shaft 18 is provided with left-handed threads and is prevented from rotating since pin 4d engages the head 3S in one of its slots. Therefore, as shaft 18 rotates clockwise, as viewed in FIG. 9, in the webbing unwind direction, the compensator screw threads itself into the shaft 13` a distance determined by the head of the thread on the screw 38. IThe lthrust plate spring 39 is thus progressively compressed to increase progressively the! force on thrust plate 37, and thereby increase the coupling force on ywheel 31. It can thus be seen that, as the effective radius of the shaft 13 and webbing 14 wound thereon `decreases to tend to lower the effective rectilinear acceleration needed to operate this device, the tension of thrust spring 39 increases to tend to raise the effective rectilinear acceleration needed to operate this device. When the shaft rotates in the windrup direction, the head 38 moves outwardly from the end of shaft 18 and the tension of thrust spring 39* is decreased. This device is thus compensated to ensure operation at one particular pre-set rectilinear acceleration.

The above-described inertia-operated safety device provides for a manual lock and an automatic'lock and for a manual release from both manual and automatic lock. In some instances of use, the manual lock and the manual unlock from the lock-up position are not necessary, there only being the requirement that the device be automatically unlocked at all times when an accelerating force of sufficient amplitude to operate the device is not present on the strap cable. The novel automatic device utilized to unlock the safety mechanism automatically is shown in FIGS. l2 and 12a, it being noted that the following structural elements disclosed above and utilized in the manual unlocking operation are omitted from the device and replaced by a simple dog drag spring 7i): the main control shaft 63, external control lever 64, inner control lever 65, torque pin 66, dog retraction lever 67, control shaft spring 68, and pin 69. The U-shaped dog drag spring 7d is securely aflixed to the lock dog 72, the fingers of this spring slidably gripping the sides of the ratchet wheel 31. This spring 70 senses the direction of rotation of the ratchet wheel 30, and, when the ratchet wheel is turning in a direction such that the strap is being pulled out from the safety device, the dog is urged in a direction to engage the ratchet wheel 3i). When the ratchet wheel rotates in a direction to Wind up the strap on the reel, the dog is urged in a direction to move away from the ratchet wheel Sti. During the period that the strap is being played out from the device at an acceleration less than the predetermined acceleration of operation, the sear arm 55 engaging the finger '74 prevents the lock dog from engaging the ratchet wheel 36. When the predetermined acceleration is reached, the sear 49 is lifted and the lock dog 72 is carried into engagement with the ratchet teeth on the ratchet wheel 30 by the dog drag spring 70. When the ratchet wheel 3S turns in the wind-up rotational direction, the dog is moved away from the ratchet wheel and the sear arm S5 falls behind the finger 74, thus unlocking the reel.

Since many changes could be made in lthe above construction and many apparently widely different embodiments-of this invention could be made without departing from the sccope thereof, it is intended that all matter contained in the above description or shown in the accompanyingdrawings shall be interpreted as illustrative land not in a'limiting sense.

What is claimed is:

l. An inertia-operated safety device for mounting in a vehicle to restrain the movement of a body within the vehicle when the body is subjected to accelerated movements relative to the vehicle comprising a tension member for coupling to the body, a reel on which Isaid tension member is wound, yieldable resilient means coupled to said reel tensioned so as to urge said reel in the direction to wind up said tension member thereon, said reel being rotatable against the tension of the resilient means in a direction to unwind the tension member from the reel responsive to movements of the body, a fiywheel rotatably mounted in axial alignment with said reel, yieldable means coupling said iiywheel to said reel to rotate said flywheel in unison with said reel during rotation thereof in the unwind direction below a certain acceleration, said yieldable means yielding during rotation of said reel at said certain acceleration whereby said reel rotates relative to said flywheel, locking means operated in response to the yielding of said yieldable means for locking said reel against further rotation in the unwind direction, said locking 1means having a normal position it assumes when the reel is in an unlocked condition and a lock position when the reel has been locked agai-nst -further unwind of the tension member, manually operated means for moving said locking means from said lock position to said normal position, and means operating to prevent relative rotation between said flywheel and said reel during that short period of time when said locking means is first moved from' its lock position and being returned to its normal position.

2. An inertia-operated safety device for mounting in a vehicle to restrain the movement of a body within the vehicle when the body is subjected to accelerated movements relative to the vehicle comprising a tension member for coupling to the body, a reel on which said tension member is wound, yieldable resilient means coupled to said reel tensioned so as to urge said reel in the direction to wind up said tension member thereon, said reel `being rotatable against the tension of the resilient means in a direction to unwind the tension member from the reel responsive to movements of the body, a flywheel rotatably mounted in axial alignment with said reel, yieldable means wheel, said thrust plate driving said :flywheel through said yieldable coupling means to rotate said ywheel in unison with said reel during rotation thereof in the unwind direction belowa certain acceleration, said yieldable coupling means yielding during rotation of said reel at said certain acceleration whereby said reel and thrust plate coupling said tlywheel to said reel to rotate said ilywheel in unison with said reel during rotation thereof in the unwind direction below a certain acceleration, said yieldable means yielding during rotation of said reel at said certain acceleration whereby said reel rotates relative to said ywheel, locking means operated in response to the yielding of said yieldable coupling means for locking said4 reel against further rotation in the unwind direction, said locking means including a spring-loaded lock dog, said lock dog having a normal position it 4assumes when the reel is in -an unlocked condition and ia lock position when the reel has been locked against further unwind of the tension member, manually operated means for moving said lock dog from said locked position to said normal position, and means controlled by said manually operated means for preventing relative rotation between said flywheel and said reel during that short period of time when said lock dog is first moved from its lock position and is being returned to its normal position.

3. An inertia-operated safety device for mounting in a vehicle to restrain the movement of fa body within the vehicle when the body is subjected to accelerated movements relative to the vehicle comprising a tension member for coupling to fthe body, a reel on which said tension member is wound, yieldable resilient means coupled to said reel tensioned so as to urge said reel in the direction yto wind up said tension member thereon, said reel being rotatable against the tension of the resilient means in a direction to unwind the tension member fnom the reel yresponsive to movements of the body, a flywheel rotatably mounted in axial alignment with said reel, a thrust plate mounted for rotational movement with said reel, yieldable means for coupling said thrust plate to said yrotate relative to said flywheel, locking means operated in response to the yielding of said yieldable coupling means for locking said reel yagainst further rotation in the unwind direction, said locking means having a -normal position it assumes when the reel is in an unlocked condition and a lock position when `the reel has been locked against further unwind of the tension member, manually operated means for moving said locking means from said lock position to said normal position, and means controlled by said manually operated means operative to prevent said yieldable coupling means from yielding during that short period of time when said lock dog is rst removed from its look position and is being returned to its normal position, whereby said safety device is prevented from automatically locking up during that short period of time during manual release.

4. An inertia-operated safety device as claimed in claim 3 wherein said yieldable coupling means permits longitudinal 'axial movement of said thrust plate during relative rotation -between said flywheel land said reel and thrust plate upon automatic lock-up, said means operative to prevent relative Irotation between said ywheel and said reel and thrust plate during the period of release of said lock dog comprising a sear lever coupled to said thrust plate for preventing axial longitudinal movement of said thrust plate lthereby preventing relative rotational movement between said ilywheel and said reel and thrust plate.

5. An inentiaaoperated safety device as claimed in claim 4 wherein said yieldable coupling means includes a plurality of steel balls sandwiched between said thrust plate and said flywheel and nestling in indentlations in the surfaces thereof and a spring for urging said thrust plate against said steel balls and ywheel, said steel balls moving out of said indentations on relative rotation between said llywheel and said reel and thrust plate and producing axial longitudinal movement of said Ithrust plate against `said spring means.

References Cited in the le of this patent UNITED STATES PATENTS 2,845,234 Cushman et al. July 29, 19'58 2,886,259 Baarecki May 12, 1959 3,018,065 Cushman et al Ian. 23, 1962 FOREIGN PATENTS 805,358 Great Britain Dec. 3, 1958 

1. AN INERTIA-OPERATED SAFETY DEVICE FOR MOUNTING IN A VEHICLE TO RESTRAIN THE MOVEMENT OF A BODY WITHIN THE VEHICLE WHEN THE BODY IS SUBJECTED TO ACCELERATED MOVEMENTS RELATIVE TO THE VEHICLE COMPRISING A TENSION MEMBER FOR COUPLING TO THE BODY, A REEL ON WHICH SAID TENSION MEMBER IS WOUND, YIELDABLE RESILIENT MEANS COUPLED TO SAID REEL TENSIONED SO AS TO URGE SAID REEL IN THE DIRECTION TO WIND UP SAID TENSION MEMBER THEREON, SAID REEL BEING ROTATABLE AGAINST THE TENSION OF THE RESILIENT MEANS IN A DIRECTION TO UNWIND THE TENSION MEMBER FROM THE REEL RESPONSIVE TO MOVEMENTS OF THE BODY, A FLYWHEEL ROTATABLY MOUNTED IN AXIAL ALIGNMENT WITH SAID REEL, YIELDABLE MEANS COUPLING SAID FLYWHEEL TO SAID REEL TO ROTATE SAID FLYWHEEL IN UNISON WITH SAID REEL DURING ROTATION THEREOF IN THE UNWIND DIRECTION BELOW A CERTAIN ACCELERATION, SAID YIELDABLE MEANS YIELDING DURING ROTATION OF SAID REEL AT SAID CERTAIN ACCELERATION WHEREBY SAID REEL ROTATES RELATIVE TO SAID FLYWHEEL, LOCKING MEANS OPERATED IN RESPONSE TO THE YIELDING OF SAID YIELDABLE MEANS FOR LOCKING SAID REEL AGAINST FURTHER ROTATION IN THE UNWIND DIRECTION, SAID LOCKING MEANS HAVING A NORMAL POSITION IT ASSUMES WHEN THE REEL IS IN AN UNLOCKED CONDITION AND A LOCK POSITION WHEN THE REEL HAS BEEN LOCKED AGAINST FURTHER UNWIND OF THE TENSION MEMBER, MANUALLY OPERATED MEANS FOR MOVING SAID LOCKING MEANS FROM SAID LOCK POSITION TO SAID NORMAL POSITION, AND MEANS OPERATING TO PREVENT RELATIVE ROTATION BETWEEN SAID FLYWHEEL AND SAID REEL DURING THAT SHORT PERIOD OF TIME WHEN SAID LOCKING MEANS IS FIRST MOVED FROM ITS LOCK POSITION AND BEING RETURNED TO ITS NORMAL POSITION. 